The invention pertains to stove grates that prevent ash build-up and clinker formation of a particulate fuel mass in a stove. More particularly, the present invention pertains to reciprocating stove grates having orifices therein that allow air flow through the grate in order to prevent ash build-up and clinker formation.
In general, suspension burning is a technique known in the art that is employed to physically suspend difficult to combust material in the air in order to improve the combustion. However, the air flow employed in suspension burning is not used for ash removal or as an impediment to clinker formation. Also known is a shaker grate that has bars that can be agitated or pivotally displaced in order to break-up clinker. However, the shaker grate does not prevent the formation of ash or clinker, it only loosens clinker that has already formed.
U.S. Pat. No. 2,932,264 issued to Hurst discloses a stoker having a movable grate with a plurality of openings therein. The grate is inclined, with a coal hopper disposed at one end. A coal bed covers the grate, which is very slowly reciprocated. The coal bed moves as a unit with the grate and the openings therein as the grate moves to the left (as shown in FIG. 2 of Hurst). This allows additional coal from the hopper to be fed onto the right side of the grate. Then, as the grate moves to the right, part of the coal bed is forced against the rear wall of the hopper such that the coal bed moves left relative to the rightward movement of the grate, thus pushing coal ash off of the left end of the grate. The purpose of the reciprocating grate of Hurst is to feed coal, not the efficient burning of lower quality pellets by ash dissipation through the grate holes which prevents clinker formation. In fact, Hurst admits clinker formation at column 3, lines 3 through 8, and expressly avoids removal of ash through the grate holes at column 3, lines 15 through 18. Finally, the grate of Hurst does not reciprocate in both directions under a stable fuel mass, but instead the grate moves with the moving coal bed in a first direction and moves in the opposite direction of the coal bed in a second direction.
U.S. Pat. No. 4,537,140 issued to Baker; U.S. Pat. No. 4,665,840 issued to Yarnell; and U.S. Pat. No. 2,879,727 issued to Walters all disclose non-moving fuel grates having holes therein. The Baker patent discloses a feed system whereby the grate receives fuel from a movable carpet. Both the Yarnell and Walters patents disclose grates that are gravity fed.
A need thus exists for a stove grate that prevents ash build-up and clinker formation of low quality particulate fuel during burning in a pellet stove or the like.
A need exists for the above type of grate in which a plurality of openings therein allow air flow through the grate in order to prevent ash build-up and clinker formation.
A need also exists for the above type of grate having openings therein in which the grate reciprocates relative to the particulate fuel mass to channel a constant stream of stove air flow through various portions of the particulate fuel mass in order to prevent ash build-up and clinker formation.
Finally, a need exists for the above type of reciprocating grate having openings therein in which few moving parts are required to cause reciprocation of the grate.